The predominant method of ginning cotton today involves the use of disk-like toothed members rotating side by side with ribs between the spaced-apart disks. The seed cannot pass through the gaps between the ribs whereas the lint fibers pass through the gaps as the lint is impaled on the teeth of the disk-like members. This process inherently breaks an appreciable percentage of fibers, and furthermore, the tips of the teeth on the disk-like members remove some of the short linter fibers and cut into some of the seed coats, creating seed coat fragments with fibers attached to them which are very difficult to remove in the later cleaning processes.
Another method of ginning cotton employs a cylindrical roller covered with an animal hide, such as walrus, or fiber-impregnated rubber packing-like material. This roller is pressed against a stationary "knife". Seed cotton is dropped onto the surface of the roller and the cotton fibers are drawn between the roller surface and the stationary knife while the seed are stripped back by the nose of the stationary knifes. Thus the lint fibers pass under the stationary knife and the seeds are ejected over the top of stationary knife. In the latest technology, a rotary bladed or finned cylinder (rotary knife) assists in bringing the seed cotton to the pinch point between the stationary knife and the roller and in pulling the seed away from the pinch point.
The roller ginning process has certain advantages over the saw ginning process but is not fully adaptable to ginning upland or fuzzy seed cotton. The advantages of the current roller gin processes over the saw gin processes over the saw gin process are that there is less fiber breakage and less "nepping" of the fibers. The disadvantage of the current roller ginning technology is the removal of some of the short linter fibers along with the desirable long fibers, and thus the lint contains a high percentage of short, undesirable fiber. Furthermore, on upland cotton, the current roller gin processes are even slower than they are in ginning extra long staple varieties of cotton that do not contain linter fibers.
New textile mill processes are also being introduced that are best exploited with more uniform fiber length, and less short fiber and neps in the fiber.